Appropriate lateral joint laxity in flexion for optimizing patient satisfaction following bicruciate-stabilized total knee arthroplasty.

Abstract

Previous studies have reported that lateral laxity in flexion following bicruciate-stabilized total knee arthroplasty (BCS TKA) can influence patient-reported outcomes. However, the optimal degree of lateral laxity in flexion remains unclear. This study aimed to determine the appropriate lateral laxity required to achieve good patient satisfaction following BCS TKA. A total of 154 knees that underwent BCS TKA between January 2018 and January 2024 were retrospectively reviewed. Lateral joint laxity was assessed intraoperatively. Patient satisfaction was evaluated 1 year postoperatively using a 5-point scale and a visual analog scale (VAS). (ROC) curve analysis was performed to determine the optimal cut-off value for lateral joint laxity at 90° flexion (LJL). A positive correlation was observed between LJL and patient satisfaction (r = 0.272, P < 0.01). Patients in the dissatisfied group had a significantly smaller LJL than those in the satisfied group (1.5 ± 2.8 mm vs. 4.0 ± 2.6 mm, P < 0.01). ROC analysis identified 3 mm as the optimal cut-off value for LJL (area under the curve = 0.74). Patients were subsequently divided into three groups based on LJL measurements: ≤ 3 mm (Group 1), 3 mm < LJL < 6 mm (Group 2), and ≥ 6 mm (Group 3). Groups 2 and 3 demonstrated significantly higher patient satisfaction rates and VAS scores than Group 1, with no significant difference observed between Groups 2 and 3. Lateral joint laxity exceeding 3 mm at 90° of flexion may help prevent patient dissatisfaction following BCS TKA.